Scientists at Stanford develop water splitter that runs on ordinary AAA battery
news.stanford.edu
news.stanford.edu
First, yes this is cool new science. No one imagined nickel would work as a water-splitting electrocatalyst. This is very surprising, and awesome.
Second, the point of water-splitting is obviously not power generation. It's power storage, just like a battery, but with better transport and storage characteristics.
But I agree with you, efficient-cheap catalyst is needed indeed. I'd like to know the efficiency of the system though...
A cylinder full of compressed hydrogen weighs less than a trunk full of AAA batteries, which cuts into economy.
The clunky bank of AAA batteries can be stationary in some water-splitting plant, whereas the hydrogen is light and portable.
Not true. It has been known since the 1950s (and likely earlier) that Ni oxides can function as water splitting catalysts (both for hydrogen evolution and oxygen evolution half reactions).
So what makes a hydrogen exposed freezing tank better suited for transport and storage than a chemical battery?
And to answer your question, much better energy density by mass.
Some little PDFs about the hurdles of hydrogen from one of my favorite tech writers:
http://www.tinaja.com/glib/resbn88.pdf
http://www.tinaja.com/glib/energfun.pdf
A hydrogen economy might be possible one day, but not until we find a natural H2 source that is as "free" as crude oil. Man made hydrogen will not work on a large scale. Electrolysis is one of the worst ways to make hydrogen, though it does have the highest "gee-whiz!" factor.
If we did have unlimited hydrogen spewing out of the ground people would seriously consider first cracking the H2 into hydrocarbons to make it easier to transport.
(Granted you'd also need to make coal out of co2, which is so much harder. but every little bit helps)
Although touted as zero-emissions vehicles, most of the cars will run on hydrogen made from natural gas, a fossil fuel that contributes to global warming. Now scientists at Stanford University have developed a low-cost, emissions-free device that uses an ordinary AAA battery to produce hydrogen by water electrolysis.
You don't agree the juxtaposition gives the impression that the latter alternative won't contribute to global warming?
Edit: just to be clear, I'm not saying the research isn't useful. My issue is with the article.
Please don't be personally rude on Hacker News. This comment would be fine without the first two sentences.
I wish there were a way for users to suggest edits to each other's comments. My bet is that most of us have no idea when our comments include superfluous stuff that could easily be edited out. Suppose there were an easy way to send pull requests on comments. One could look at the diff and, if it improved the signal/noise ratio, simply accept the changes.
HN needs more sober second thought.
We're still interested in whatever might be done to curtail such downhill slides.
Still, as a user, I don't care about voltage. How many kWh of energy does it take to produce n grams of hydrogen with this method, and how does it compare to existing methods.
Give me the highest relevant abstraction related to energy use.
Plus, all I know about hydrogen points to it not being anything close to "an ideal fuel for powering vehicles, buildings and storing renewable energy". It has very low density, requires cryogenic storage or very heavy pressure vessels, migrates through materials, and is explosive when mixed with air.
If it is a chore to use the stuff for rocket science, I don't see it becoming a reasonable power source in more casual applications.
If I am factually incorrect about anything here, I honestly do want to be told so.
With hydrogen, the issue issue is that (at least to my understanding) if you have electricity, we already have a far more efficient solution: put the electricity directly into a battery and use it to power a motor. Going the route over electrolysis->hydrogen storage->fuel cell imposes such efficiency penalties that it would need extremely compelling other advantages to be competitive, and I don't see them.
Hydrogen fuel cells also tend to be highly efficient.
The long-term performance question is interesting, though. Any idea how long the time scale would have to be before the fuel cell wins?
Sadly this is not the case. Fuel cells have similar lifespans as batteries.
If we're going to have a rational discussion about various forms of emission, we need to talk about total fuel cycle emissions, otherwise it's meaningless. Touting one small section of a fuel cycle as emissions free is at best confusing, at worst misleading.
With gasoline, the use of stored energy requires emissions.
With batteries, the use of stored energy does not require emissions.
You are creating false equivalencies, the only purpose of which is to drag down the discussion and stop the discussion.
You want to talk about fuel cycle, talk about the fuel cycle, don't say things that are blatantly false.
With gasoline, the use of stored energy requires emissions.
With batteries, the production of stored energy required emissions.
True, the analogy isn't perfect, because maybe the batteries were charged from a PV system (though in practice chances are they were not) but to call it "incredibly dishonest" and "blatantly false" seems a bit excessive, don't you think?
The point is, while using power from a battery doesn't cause any emissions, you need to know where the energy came from to make any meaningful comparisons.
At some point you have to trust the reader to understand things that are completely obvious. That's a necessary quality of good writing, even if you're adhering to the newspaper standard of targeting someone at the 8th grade reading level.
Hydrogen is not exactly the easiest compound to work with and how it is generated is a huge part of equation.
On the contrary, if they'd demoed the thing with a small solar panel I might have had some issues with it, and wanted to see some elaboration. The fundamentally good thing about the battery example is that everyone understands that making a battery costs something. IMO it's a better example than you give them credit for.
Certainly everyone reading here understands that it takes energy to make a battery, that the creators of the gadget haven't defeated the laws of thermodynamics, and so on. Hence my comment about trusting the reader.
Agree that hydrogen isn't an ideal fuel though. They're overselling that point. But the science is about how to split water efficiently. It's outside the scope of this research to address how to handle and use hydrogen after that.
In their experimental setup, they target 20 mA/cm2 current density. To achieve that, they can just increase the amount of catalyst they use. The geometric area (cm2) will remain the same, but the surface area will increase which will correspondingly raise current density. For example, one can stack sheets of carbon aerogel to achieve the same current density.
Making it more plausible I suppose. The only thing I have a problem with is that they used a battery, which required electricity to be initially charged. The electricity had to be generated somehow. If we plan to use <insert renewable energy here> to charge the batteries to split the water to generate the hydrogen to power our cars, I think very few people will be driving.
Article links to the paper. Unfortunately only the abstract is free. Seems like the advance is making it more efficient. Electrolysis at a usable level with just AAA-level voltage.
"The researchers also plan to develop a water splitter than runs on electricity produced by solar energy."
Unfortunately that approach would be less efficient that simply transferring the electrical energy to an electric motor.
Light > Electricity > Hydrogen > Electricity > Electric Motor
is longer than
Light > Electricity > Electric Motor
Did you do that when you were 9 too?
That may have been coincidence but it certainly wasn't new knowledge to me that Nickel works well as an electrode when splitting water in Hydrogen and Oxygen.
I wished I'd kept my books from childhood and I'd be able to show you. It wasn't a particular fancy set either, just a bunch of test tubes, some leads to attach to a 4.5 V flat battery (I haven't seen those in ages either) and a bunch of basic chemicals.
Using non-mobile solar cells to produce an energy-dense fuel which is portable makes sense, even if there is an efficiency hit.
Cars themselves are not efficient no matter how they are powered, because utmost efficiency in a car means lying on your back in a narrow, feather-weight, fragile aerodynamic tube with wheels, going about 25 mph max, and taking minutes to get to that speed. Forget niceties like air conditioning.